Internal high-pressure shaping method for shaping conical tubes made of metal. The invention relates to an internal high-pressure shaping method for shaping conical tubes made of metal, in particular steel, in a tool comprising a die cavity having a complex contour and two sealing pistons, by means of which the interior of the tube to be shaped is sealed at its two ends, in that the sealing pistons, which engage with the tube ends, press the tube ends against the wall of cylindrical portions at the two ends of the die cavity.
In the internal high-pressure shaping of tubes, relatively high degrees of shaping may be achieved if material is axially redisplaced during radial flaring of the tubes. In the case of cylindrical tubes, the axial redisplacement of material is unproblematic. In the case of conical tubes, on the other hand, the redisplacement is not easily possible for geometrical reasons, because there are sealing problems at the conical tube ends. In order nevertheless to allow even conical tubes to undergo internal high-pressure shaping with the axial redisplacement of material, tubes are used in which short cylindrical portions are connected to the conical part. The tool accordingly comprises correspondingly cylindrical portions on both open sides of the die cavity, so the cylindrical portions of the tool, is inserted into the tool, in that these conical ends of the tube are pressed by the sealing pistons to be introduced until they abut the cylindrical portions of the tool, optionally with redial flaring, and in that the internal high-pressure shaping process then takes place by means of at least one sealing piston acting on the end face of the associated tube end, wherein during the compression process at least on of the cylindrically flared tube ends is displaced up to the end of the associated cylindrical portion.
The object of the invention is to provide an internal high-pressure shaping method for shaping conical tubes, which allows high degrees of shaping of complex shapes and necessitates lower costs than the described method.